Does personality affect premating isolation between locally-adapted populations?

Area of Science:

• Evolutionary biology
• Animal behavior

Background:

• Premating isolation is crucial for diverging populations, with female mate choice playing a key role.
• In the *Poecilia mexicana* species complex, females from non-sulfidic habitats prefer resident males over those adapted to hydrogen sulfide (H2S)-toxic springs.
• Individual variation in mating preferences and its link to animal personality require further investigation.

Purpose of the Study:

• To investigate if consistent individual differences in animal personality predict the strength and direction of female mate choice in the *Poecilia mexicana* system.
• To determine how personality traits like exploration and boldness influence premating isolation.

Main Methods:

• Focal females were characterized for personality traits including novel object exploration, boldness, and activity in an unknown area.
• Dichotomous association preference tests were used to assess female mate choice (Strength of Preference - SOP) for resident vs. alien male phenotypes.
• The effect of male size differences on female preference was also tested.

Main Results:

• Exploration and boldness interacted to affect female strength of preference (SOP) for resident males.
• Bold females with high exploration tendencies showed stronger preferences for resident males.
• Shy or less explorative females were more likely to prefer non-resident males, increasing hybridization potential.
• Less explorative females preferred larger males when size differences were significant, but this effect diminished with smaller size differences.

Conclusions:

• Personality traits significantly influence female mate choice in a nuanced manner.
• Population-level differences in personality type distribution can either facilitate or impede reproductive isolation.
• The specific male traits influencing female mating decisions interact with personality to shape reproductive isolation outcomes.